A well-known criminal law solicitor is being sued for more than £300,000 by the legal aid commission which claims it paid him for work he never did.

Conrad Gadd, 53, who runs his own law firm in Cheltenham, Gloucestershire, is disputing the allegation by the Legal Services Commission (LSC) and has lodged a counter claim.

The LSC has issued a High Court writ claiming repayment of £233,311.37 plus interest of £72,512.10 and continuing interest of £51.14 a day.

Mr Gadd, who has been a familiar figure in the courts of Gloucestershire since he qualified as a solicitor in 1989, has defended in some high-profile cases in the county.

He has represented members of the notorious Johnson criminal family, who have plagued Gloucestershire for more than 30 years.

Many members of the Johnson clan are now serving long jail terms after a multi-million pound series of burglaries at large country homes in the Home Counties.

Mr Gadd's firm no longer undertakes legal aid work and charges £175 an hour plus VAT to represent private clients. He operates from a suite in Cheltenham's tallest building, the Eagle Star tower.

The writ from the LSC says his firm provided legal aid to clients at his offices in Gloucester and Cheltenham under contract from April 2001 to 2005. He was paid standard monthly fees plus payment for his monthly claims for work done.

The LSC says that after his contracts were terminated in March 2005, records showed his Cheltenham office had been overpaid by £167,337.92 and his Gloucester office by £65,973.45.

The LSC says it has therefore paid him £233,311.37 "for which he has provided no consideration or for which he has not submitted valid claims for work".

Mr Gadd denies he owes the money. He said: "They overpaid me and we have been in discussion for three years because they were in breach, I say, of their contract in a substantial way.

"As a result they owe me something in the region of £500,000 to £750,000.

"They were supposed to pay me at certain times and they failed to make certain payments when they should have done.

"It doesn't affect my position as a solicitor at all. It doesn't have any professional implications whatever. It's a straightforward contractual dispute."

The LSC's solicitors wrote last September demanding payment of the disputed sum, but Mr Gadd has refused, it is alleged. The lawsuit was filed in court by Adam Taylor of London based solicitors CKFT.

A statement from the LSC said: "We have a duty to ensure taxpayers' money is properly managed.

"The budget we have is used to fund advice and help for some of the most vulnerable people in society.

"Where we have a concern that a solicitor might have been overpaid for their work, we have a duty to ask that solicitor to account to us for that money and, where appropriate, to reclaim it.

"The commission has a number of arrangements in place that allow solicitors to be paid money on account for legal aid work provided they subsequently claim for the work and it is assessed by us as payable.

"Our debt recovery unit has now commenced proceedings in order to recoup the money owed to us."